Lineus sp. (Nemertea, Nemertini, Heteronemertea, Lineidae), pilidium larva, diameter 450 µm, Helgoland 08.2014. The taxon Heteronemertea in the taxon Nemertea or Nemertini develops characteristic planktonic pilidium larve (pilidium: form of roman helmet) with fore-lobe like a baseball-cap and hind lobe, at each side lateral lobes, all equipped with ciliary bands. The mouth is located between these lobes. An apical plate near the top bears a tuft of long stiff cilia. Video can be used for teaching.